Heat pump systems are well known for providing both heating and cooling by using a small amount of energy to move heat from one location to another. Heat pumps are typically used to pull heat out of the air or ground to heat a home or office building, but they can be reversed to cool a building as well. One of the biggest advantages of a heat pump over a standard heating ventilation and air conditioning (HVAC) unit is that there's no need to install separate systems to heat and cool your home. Heat pumps also work extremely efficiently, because they only transfer heat, rather than burn fuel to create it. This makes them more “green” than a gas burning furnace. In fact, they don't just heat and cool buildings. Anyone that has ever enjoyed a hot tub or heated swimming pool probably has a heat pump to thank.
While heat pump systems provide a host of benefits, there has been a long felt need to improve the efficiency and overall performance of such systems. In particular, it would be highly advantageous to accomplish this by providing an improved heat pump system incorporating an environmentally friendly (i.e., “green”) subassembly capable of efficiently raising the temperature of the hot gas line of the heat pump system. For example, it would be a tremendous benefit to provide a means for integrating an existing solar thermal assistance technology, such as a solar collector subsystem, into an existing conventional heat pump system to provide the aforementioned improved performance.
Solar heating and cooling systems use the sun as a source for energy needs. Because the sun is a renewable energy source, it has the potential to supply a home with enough power to meet its energy requirements every day. Solar energy is accumulated through a solar collector, a system that converts sunlight to usable energy by capturing and retaining heat from the sun and transferring this heat to a liquid.
Evacuated glass tubes, one form of solar collectors, provides a way in which heat loss to the environment, inherent in flat plate collectors, has been reduced. Since heat loss due to convection cannot cross a vacuum, it forms an efficient isolation mechanism to keep heat inside collector pipes. While evacuated tube technology clearly surpasses flat panel collectors or batch solar collectors for nearly all water heating applications, the advantages are truly dramatic when used for solar air conditioning and heating. This is because evacuated tube heat pipe collectors can more easily attain the higher temperature needed, they can collect and retain heat even when it is very cold outside, and they collect solar energy more evenly throughout the day resulting in lower buffer or thermal storage requirement. Generally, an evacuated tube solar collector contains several rows of glass tubes connected to a header pipe. Each tube has the air removed from it (evacuated) to eliminate heat loss through convection and radiation. Inside the glass tube, a flat or curved aluminum or copper fin is attached to a metal pipe. The fin is covered with a selective coating that transfers heat to the fluid that is circulating through the pipe.
What is desired is such an evacuated tube solar thermal assisting subsystem that can be easily integrated with, or retrofitted into, a conventional heat pump system to efficiently and effectively provide added heat to the system to extend the functionality of the heat pump system and thereby reduce the requirement to utilize electric heat strip or other alternate systems. Preferably, the system should have the inherent flexibility to be installed with any new heat pump or, alternatively, retrofitted to an existing heat pump, to boost the performance of the heat pump to provide interior heating, as well as to be connected to provide a hot water boost and pool/spa heating. This would negate the need for a separate pool heat pump. The heat pump, when used in its reverse cycle for air conditioning should, when either water heating or pool heating is desired, be able to route the hot gas through the solar collector and heat exchanger, and then back to the condenser. Preferably, the system can be prioritized to heat water when the temperature drops below a specified point. In this manner, the system would both provide free hot water and improve the air conditioning performance as the heat exchanger functions as an additional condenser. This would be particularly effective during the air conditioning cycle, where gas would not be routed through the solar collector unless water heating or pool heating is desired. In this manner, the panels would have the maximum heat available to put very hot gas into the heat exchanger to heat the water rapidly.